Web-based nightly observer's reports were inaugurated in July 1999, and so we do not have a complete set of 1999 observer reports. Before that date no electronic reporting system was used.
Nightly reports are filed by date given as the "observing day" which is the local date of the start of the night's observing. Thus, to find the observer's report for the night that began at sunset of 1999 July 23 and ended at dawn of 1999 July 24, you would refer to the report dated "1999 July 23".
Note that not all nights will have observer's logs filed, especially early in the process when the observer's were getting used to the new system.